Rayon fabric



vcially a non-woven fabric, and

3,012,925 RAYON FABRIC Horace P. Fry, Jr., West Chester, Pa.,- assignorto American Viscose Corporation, Philadelphia, Pa., a corporation ofDelaware No Drawing. Filed Nov. 26, 1958, Ser. No. 776,433

' 4 Claims. (Cl. 156-181) This invention relates to a method of making ahigh strength, low-extensibility open-mesh rayon fabric, espemoreparticularly to a method of making such a fabric from ordinary,unstrained, low-twist viscose rayon yarn.

It is an object of this invention to provide an improved method ofmaking an open-mesh rayon fabric, especially a non-wo en fabric, havinga relatively low degree of extensibility.

It is a further object to provide a method of making a non-Woven rayonfabric of low extensibility which permits the use of an aqueous adhesivesolution for binding the yarns of the fabric together at their crossingpoints.

It is still another object of the present invention to provide a methodof making a low-extensibility non-Woven rayon fabric from ordinary,unstrained, low-twist viscose rayon yarn.

Another object of the invention is to provide an economical method ofmaking a lo -extensibility open-mesh rayon fabric.

-Other and further objects, features and advantages will become apparentas the description of the invention proceeds.

The usual continuous filament viscose rayon yarn, unless highly twisted,has an extensibility of approximately 18% when dry'and 22% when wetbefore its full strength is realized andthe yarn breaks. This highextensibility can be considerably reduced, say to about 8% or even less,if during initial manufacture or subsequently the yarn is subjected to aslashing operation wherein the yarn is wetted and then held undertension while drying. However, the reduced extensibility brought aboutby slashing is destroyed if the yarn is subsequently gotten wet andallowed to dry in a rel-axed or untensioned condition and consequentlyslashing is ordinarily only employed when the yarn is to be used in amanner wherein it is protected from water, as for example, for tirecord.

Open-mesh fabric known as scrim, which may be either woven or non-wovenhas a wide variety of uses. Obviously, in the case of non-woven scrim,the yarns making up the fabric must be secured together at theircrossing points in order to hold the fabric together and this iscustomarily accomplished by means of an adhesive. It is also customaryto employ an adhesive to secure the yarns together at their crossingpoints in woven scrim, especially in the case of wide mesh scrim.Because the individual threads or yarns of scrim are not closely packedtogether as they are in a closely woven fabric, the scrim has anextensibility substantially equal to that of the individual yarns ofwhich it is formed. Thus, scrim formed of ordinary, unslashed, low-twistrayon yarn has an extensibility of approximately 18% when dry and 22%when wet. 'Scrim formed of slashed rayon yarn has a much lowerextensibility but the adhesive employed must not contain water or beapplied as a water emulsion or suspension unless the individual yarnsare maintained under tension until the fabric is completely dry, forotherwise the low-extensibility characteristic of the yarn is destroyed,as mentioned above. While there are certain volatile adhesives which maybe used which do not impair the low-extensibility of the yarn, thesecreate undesirable and expensive problems in connection with solventrecovery, ventilation, fire hazard, etc. On the other hand, when anaqueous ad- 3,012,925 Patented Dec. 12 1961 hesive liquid is employed,the mechanisms necessary to maintain the yarn under tension until dryare com: plicated and the fabric forming operation generally has toproceed at a slower rate. While a scrim of low extensibility is ideallysuited as a reinforcing lamina for paper or other sheet material, theabove-mentioned problems in connection with forming the scrim of alowextensibility rayon yarn have limited its use for this purpose.

According to the present invention an ordinary, unslashed, low twist,viscose rayon yarn is employed to obtain an'open-rnesh fabric having thelow extensibility of a fabric formed of a slashed yarn. Furthermore, theyarn is neither dried nor sized and is therefore considerably lessexpensive than that heretofore employed in making fabric.

While there are several extensively used processes for making viscoserayon yarn, differing in specific detail and in the order in which someof the steps are performed, in general the essential steps can be saidto comprise extruding viscose through a spinneret into an acid bathwhich coagulates the viscose into a strand, stretching the strand toorient the molecules, washing the strand in a relaxed or untensionedstate to remove excess acid, and winding it into a package. Thespinneret generally contains a fairly large number of holes or orifreesso that the strand is composed of a multiplicity of filaments and thereare usually a number of additional steps'iu the process, known as aftertreatments, but these need not be enumerated here. There is, however,one other stepusually considered a step in the manufacturing processwhich requires a energy and which in some processes involves manualmanipulation of the yarn. This is the drying of the yarn and when makingthe fabric in accordance with the present invention this expensive, andin some instances time-consuming, step is eliminated.

In the so-called continuous process, the yarn passes through a number oftreating baths or otherwise has applied thereto at different times anumber of liquids, after which the yarn passes through a drying chamberor around heated rollers and finally is wound or collected on a bobbin.With the present invention, as noted above, the drying stage iseliminated and the last bath or liquid applying station is used to applyan aqueous adhesive solution to the yarn which is then immediately woundinto a package. In order that the collected yarn will have a uniformcoating of adhesive, an excess amount may be applied and the excessremoved by a wiper before collecting the yarn. While there are a largenumber of adhesives which may be employed, polyvinyl alcohol, animalglue, oarboxymethyl cellulose and aqueous latex emulsions are suggestedas suitable.

In the so-called pot spinning process, the yarn is collected in arapidly rotating pot or bucket right after the stretch orientation stepor after the initial washing, the after treatments being performed whilethe yarn is in the form of a cake. If the yarn to be used in practicingthe present invention is made by this process, the aqueous adhesiveliquid, which may be the same as mentioned above, is applied to the yarnin cake form after the usual after treatments. The adhesive may beapplied in an excess amount and the excess removed by centrifuging toleave a uniform coating. The yarn may either be left in cake form orwound onto a bobbin but in either event it is not dried.

The yarn prepared by either of the above methods is stored in a highlyhumid atmosphere to prevent the adhesive from drying. It is then formedinto an openmesh fabric either by weaving on a loom or on any of variousknown scrim making machines wherein the fill strands are laid in spacedparallel arrangement over the considerable amount of spaced: warpstrands. Thus the fabric is formed from ordinary stretch oriented butunstrained yarn. The adhesive coating is undried at the time offormation of the fabric and as will be appreciated the adhesive, whilestill wet, serves as a lubricant and eliminates the necessity foremploying the usual sizing material.

As previously noted, the thus formed. fabric. has. an extensibilitysubstantially thev same as that of the; yarn. and, since the yarn hasnot been slashed or. driedv under. strain, this extensibility is about22% while the fabri'cis still wet. After passing throughv the loom orscrim making machine, the fabric is led through aitenterv frame anddried'while heldtaut by; the tenter frame to thus-prevent shrinkage andimposed internal strains on the yarn. The drying of course sets theadhesive and the tension imposed by the tenter frame causestheextensibility ofthe yarnand" the fabric to be reduced from about 22% toabout 8%. g If desired, and it frequently will be desired,, theextensibility may be reduced even more by actually stretching the fabricon the tenter frame before drying. it is to be noted that the dryingstep normally-employed in manufacturing the yarn has actually beeneliminated and not merely postponed until after the formation of thefabric because if aqueous adhesive solutions are used in the making ofthe fabric, the fabric would have to be dried anyway evenif made frominitially dry yarn. The

advantages of employing aqueous adhesive, solutionshave:

previously been alluded to but it is WOl'th; repeating thatthey areinexpensive and much easier to use than are adhesives containing avolatile solvent.

Having thus. described the inventiomwhat is claimed is: 1. A method ofmaking an open-meshtrayon fabric, comprising extruding viscose into anacid spin bath to forma regenerated cellulose yarn strand, stretchingthe.

strand to orient the molecules and impart strength to the yarn, washingthe yarn,,applyin'g an adhesiveto the. yarn,

packaging the yarnwhile Wet, maintaining the packaged;

yarn in a highly humid atmosphere to prevent drying, disposing aplurality of suchv yarns While. wet in overlapping relationship toprovide an openemesh fabric,

tautening the fabric, and holding thefabric taut while it isdryingtothereby stress the yarnand reduce the extensibility of the fabric. I

2. Amethod of making a non-woven open-meshrayon a holding the fabrictaut while. it is drying "to thereby stress the yarn and reduce theextensibility of the fabric.

3. A method of making a non-woven rayon fabric, comprising extrudingviscose into. an acid spin bathto form a regenerated cellulose-yarn,strand, stretching the strandto. orient the, molecules and impartstrength to the yarn, releasing the tension on the strand, washing the.

strand, applying an aqueous adhesive liquidv to the strand, collectingthe. strand while wet; into a plurality of packages, withdrawing strandsfrom the packageswhilev wet and disposing the same in overlappingrelationship to provide a non-woven fabric, stretching theyfabric in amanner to tension, all the strands thereof to reduce the extensibilityof the fabric, and maintaining the fabric in its thus stretchedcondition untildry.

4.: A method of makng an open-mesh rayon fabric,

comprising extruding; viscose into anacidaspin bath to forrnaregenerated cellulose strand; stretching; the strand toorientthemolecules and impart strength to the strand,

washing the strand, applying an aqueous adhesive liquid.

tothe, strand, collecting the strandiwhile-wet into aplurality ofpackages, withdrawing a plurality of strands from the packages while Wetand disposing the, same in.

overlapping relationship to form an open-mesh, nonwoven fabric,stretching the fabricto reduce the extensibility of the yarn, and dryingthe fabric while in its.

stretched condition.

References Cited in therfile ofthis'patent UNITED STATES PATENTS2,874Q729 Ball -s Feb. 24, 1959 FOREIGN PATENTS Great Britain May 23,1946, v

1. A METHOD OF MAKING AN OPEN-MESH RAYON FABRIC, COMPRISING EXTRUDING VISCOSE INTO AN ACID SPIN BATH TO FORM A REGENERATED CELLULOSE YARN STRAND, STRETCHING THE STRAND TO ORIENT THE MOLECULES AND IMPART STRENGTH TO THE YARN, WASHING THE YARN, APPLYING AN ADHESIVE TO THE YARN, PACKAGING THE YARN WHILE WET, MAINTAINING THE PACKAGED YARN IN A HIGHLY HUMID ATMOSPHERE TO PREVENT DRYING, DISPOSING A PLURALITY OF SUCH YARNS WHILE WET IN OVERLAPPING RELATIONSHIP TO PROVIDE AN OPEN-MESH FABRIC, TAUTENING THE FABRIC, AND HOLDING THE FABRIC TAUT WHILE IT IS DRYING TO THEREBY STRESS THE YARN AND REDUCE THE EXTENSIBILITY OF THE FABRIC. 